/*
 * hdlc.cpp
 *
 *  Created on: 20/08/2013
 *      Author: Alejandro Santos LU4EXT alejolp@gmail.com
 */
/*
 *      hdlc.c -- hdlc decoder and AX.25 packet dump
 *
 *      Copyright (C) 1996
 *          Thomas Sailer (sailer@ife.ee.ethz.ch, hb9jnx@hb9w.che.eu)
 *
 *      This program is free software; you can redistribute it and/or modify
 *      it under the terms of the GNU General Public License as published by
 *      the Free Software Foundation; either version 2 of the License, or
 *      (at your option) any later version.
 *
 *      This program is distributed in the hope that it will be useful,
 *      but WITHOUT ANY WARRANTY; without even the implied warranty of
 *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *      GNU General Public License for more details.
 *
 *      You should have received a copy of the GNU General Public License
 *      along with this program; if not, write to the Free Software
 *      Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */


#include <cstring>
#include <iostream>

#include "hdlc.h"
#include "multimon_utils.h"
#include "extmodem.h"
#include "extconfig.h"


namespace extmodem {

namespace {

static const unsigned short crc_ccitt_table[] = {
        0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
        0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
        0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
        0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
        0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
        0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
        0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
        0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
        0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
        0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
        0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
        0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
        0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
        0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
        0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
        0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
        0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
        0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
        0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
        0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
        0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
        0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
        0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
        0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
        0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
        0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
        0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
        0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
        0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
        0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
        0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
        0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78
};

}

hdlc::hdlc(modem* em) : em_(em) {
	name_ = "AFSK1200";
	init();
}

hdlc::~hdlc() {

}

void hdlc::init() {
	std::memset(&hdlc_, 0, sizeof(hdlc_));
}

void hdlc::rxbit(int bit) {
	hdlc_.rxbitstream <<= 1;
	hdlc_.rxbitstream |= !!bit;
	if ((hdlc_.rxbitstream & 0xff) == 0x7e) {
		if (hdlc_.rxstate && (hdlc_.rxptr - hdlc_.rxbuf) > 2)
			ax25_dispatch_packet(hdlc_.rxbuf, hdlc_.rxptr - hdlc_.rxbuf);
		hdlc_.rxstate = 1;
		hdlc_.rxptr = hdlc_.rxbuf;
		hdlc_.rxbitbuf = 0x80;
		return;
	}
	if ((hdlc_.rxbitstream & 0x7f) == 0x7f) {
		hdlc_.rxstate = 0;
		return;
	}
	if (!hdlc_.rxstate)
		return;
	if ((hdlc_.rxbitstream & 0x3f) == 0x3e) /* stuffed bit */
		return;
	if (hdlc_.rxbitstream & 1)
		hdlc_.rxbitbuf |= 0x100;
	if (hdlc_.rxbitbuf & 1) {
		if (hdlc_.rxptr >= hdlc_.rxbuf + sizeof(hdlc_.rxbuf)) {
			hdlc_.rxstate = 0;
			verbprintf(0, "Error: packet size too large\n");
			return;
		}
		*hdlc_.rxptr++ = hdlc_.rxbitbuf >> 1;
		hdlc_.rxbitbuf = 0x80;
		return;
	}
	hdlc_.rxbitbuf >>= 1;
}

void hdlc::ax25_dispatch_packet(unsigned char *bp, unsigned int len) {

	if (!check_crc_ccitt(bp, len))
		return;
        
	// The "bp" buffer contains the CRC at the end!
	frame_ptr new_frame(new frame(bp, len - 2));

	// ax25_print_packet(new_frame, len - 2, name_.c_str(), 0);
	
	if (config::Instance()->debug()) {
		new_frame->print(name_.c_str());
	}

	em_->dispatch_packet(new_frame);
}

int check_crc_ccitt(const unsigned char *buf, int cnt) {
	unsigned int crc = 0xffff;

	for (; cnt > 0; cnt--)
		crc = (crc >> 8) ^ crc_ccitt_table[(crc ^ *buf++) & 0xff];
	return (crc & 0xffff) == 0xf0b8;
}

int calc_crc_ccitt(const unsigned char *buf, int cnt) {
	unsigned int crc = 0xffff;

	for (; cnt > 0; cnt--)
		crc = (crc >> 8) ^ crc_ccitt_table[(crc ^ *buf++) & 0xff];
	return (crc & 0xffff) ^ 0xffff;
}

void ax25_print_packet(unsigned char *bp, unsigned int len, const char* name, int has_crc)
{
	unsigned char v1 = 1, cmd = 0;
	unsigned char i, j;

	std::cerr.sync_with_stdio(true);

	if (!bp || len < 10)
		return;

#if 0
	if (!check_crc_ccitt(bp, len))
		return;
#endif

#if 0
	for (i=0; i<len;++i) {
		verbprintf(0, "%02x ", bp[i]);
	}
	verbprintf(0, "\n");
#endif

	int crc;
	if (has_crc) {
		len -= 2;
		crc = *((unsigned short*)&bp[len]);
	} else {
		crc = calc_crc_ccitt(bp, len);
	}

	if (bp[1] & 1) {
		/*
		 * FlexNet Header Compression
		 */
		v1 = 0;
		cmd = (bp[1] & 2) != 0;
		verbprintf(0, "%s: fm ? to ", name);
		i = (bp[2] >> 2) & 0x3f;
		if (i)
			verbprintf(0, "%c", i + 0x20);
		i = ((bp[2] << 4) | ((bp[3] >> 4) & 0xf)) & 0x3f;
		if (i)
			verbprintf(0, "%c", i + 0x20);
		i = ((bp[3] << 2) | ((bp[4] >> 6) & 3)) & 0x3f;
		if (i)
			verbprintf(0, "%c", i + 0x20);
		i = bp[4] & 0x3f;
		if (i)
			verbprintf(0, "%c", i + 0x20);
		i = (bp[5] >> 2) & 0x3f;
		if (i)
			verbprintf(0, "%c", i + 0x20);
		i = ((bp[5] << 4) | ((bp[6] >> 4) & 0xf)) & 0x3f;
		if (i)
			verbprintf(0, "%c", i + 0x20);
		verbprintf(0, "-%u QSO Nr %u", bp[6] & 0xf,
				(bp[0] << 6) | (bp[1] >> 2));
		bp += 7;
		len -= 7;
	} else {
		/*
		 * normal header
		 */
		if (len < 15)
			return;
		if ((bp[6] & 0x80) != (bp[13] & 0x80)) {
			v1 = 0;
			cmd = (bp[6] & 0x80);
		}
		verbprintf(0, "%s: fm ", name);
		for (i = 7; i < 13; i++)
			if ((bp[i] & 0xfe) != 0x40)
				verbprintf(0, "%c", bp[i] >> 1);
		verbprintf(0, "-%u to ", (bp[13] >> 1) & 0xf);
		for (i = 0; i < 6; i++)
			if ((bp[i] & 0xfe) != 0x40)
				verbprintf(0, "%c", bp[i] >> 1);
		verbprintf(0, "-%u", (bp[6] >> 1) & 0xf);
		bp += 14;
		len -= 14;
		if ((!(bp[-1] & 1)) && (len >= 7))
			verbprintf(0, " via ");
		while ((!(bp[-1] & 1)) && (len >= 7)) {
			for (i = 0; i < 6; i++)
				if ((bp[i] & 0xfe) != 0x40)
					verbprintf(0, "%c", bp[i] >> 1);
			verbprintf(0, "-%u", (bp[6] >> 1) & 0xf);
			bp += 7;
			len -= 7;
			if ((!(bp[-1] & 1)) && (len >= 7))
				verbprintf(0, ",");
		}
	}
	if (!len)
		return;
	i = *bp++;
	len--;
	j = v1 ?
			((i & 0x10) ? '!' : ' ') :
			((i & 0x10) ? (cmd ? '+' : '-') : (cmd ? '^' : 'v'));
	if (!(i & 1)) {
		/*
		 * Info frame
		 */
		verbprintf(0, " I%u%u%c", (i >> 5) & 7, (i >> 1) & 7, j);
	} else if (i & 2) {
		/*
		 * U frame
		 */
		switch (i & (~0x10)) {
		case 0x03:
			verbprintf(0, " UI%c", j);
			break;
		case 0x2f:
			verbprintf(0, " SABM%c", j);
			break;
		case 0x43:
			verbprintf(0, " DISC%c", j);
			break;
		case 0x0f:
			verbprintf(0, " DM%c", j);
			break;
		case 0x63:
			verbprintf(0, " UA%c", j);
			break;
		case 0x87:
			verbprintf(0, " FRMR%c", j);
			break;
		default:
			verbprintf(0, " unknown U (0x%x)%c", i & (~0x10), j);
			break;
		}
	} else {
		/*
		 * supervisory
		 */
		switch (i & 0xf) {
		case 0x1:
			verbprintf(0, " RR%u%c", (i >> 5) & 7, j);
			break;
		case 0x5:
			verbprintf(0, " RNR%u%c", (i >> 5) & 7, j);
			break;
		case 0x9:
			verbprintf(0, " REJ%u%c", (i >> 5) & 7, j);
			break;
		default:
			verbprintf(0, " unknown S (0x%x)%u%c", i & 0xf, (i >> 5) & 7, j);
			break;
		}
	}
	if (!len) {
		verbprintf(0, "\n");
		return;
	}
	verbprintf(0, " pid=%02X crc=%04x\n", *bp++, crc);
	len--;
	j = 0;
	while (len) {
		i = *bp++;
		if ((i >= 32) && (i < 128))
			verbprintf(0, "%c", i);
		else if (i == 13) {
			if (j)
				verbprintf(0, "\n");
			j = 0;
		} else
			verbprintf(0, ".");
		if (i >= 32)
			j = 1;
		len--;
	}
	if (j)
		verbprintf(0, "\n");
}

} /* namespace extmodem */
